The present invention relates to a device for controlling a turbocharger having a rotatable shaft on which a motor/generator electric rotary machine is mounted.
There have been proposed various systems in which a turbocharger is mounted on the exhaust pipe of an internal combustion engine on a motor vehicle and has a rotatable shaft to which a motor/generator is directly coupled for the recovery of the energy of exhaust gases.
Japanese Patent Application No. 60-188827 discloses, as one such system, a device for controlling a turbocharger associated with an internal combustion engine to operate the motor/generator selectively as a generator or a motor dependent on the rotational speed of the engine and the load on the engine.
In the proposed device disclosed in the above application, when the motor/generator operates as a generator, an electric load or a battery is supplied with generated electric power, and when the motor/generator operates as a motor, the supercharging operation of the turbocharger is assisted to increase the output power of the engine. The earlier controlling device however does not have a means for optimizing the boost pressure of the turbocharger according to changes in the running conditions of the motor vehicle. Therefore, even when the motor vehicle is running under conditions which require quick acceleration, the turbocharger tends to suffer an insufficient boost pressure, and desired acceleration cannot be achieved.